In a control unit that is integrated with a motor so as to be coaxial with an output shaft of the motor, main constituent components of the control unit may include a control board installed with a CPU, an inverter circuit that supplies power to the motor, a frame that connects the control board to the inverter circuit, a connector, and a case in which these components are housed.
Here, the frame connects the control board to the inverter circuit both electrically and mechanically, and moreover, the other components are installed thereon. As a result, electric connection and mechanical connection locations have complicated shapes.
Furthermore, as regards electric wiring of the frame, the frame is formed from insulating resin and molded by insert molding, and conductive plates forming + and − lines of a power supply system, for example, are extended through the interior thereof.
At this time, large, high-speed switching currents must be passed through the conductive plates of the power supply system in order to supply power to a winding of the motor, and therefore the conductive plates become a source of noise radiation to the control board including the CPU, which is disposed in the vicinity thereof.
Hence, to solve this problem, a control unit (a control device) having: a semiconductor switching element that forms a three-phase bridge circuit for controlling a current of an electric motor; a capacitor that suppresses a ripple component of the current flowing through the electric motor; a coil that reduces noise generated during a switching operation of the semiconductor switching element; a power circuit portion that includes the semiconductor switching element, the capacitor, and the coil; a heat sink on which the power circuit portion is installed in order to dissipate heat generated by the power circuit portion; and a control board installed with a microcomputer that generates a drive signal for driving the semiconductor switching element, wherein the semiconductor switching element and the capacitor are disposed concentrically as a pair on each arm of the three-phase bridge circuit, and connecting members that electrically connect the arms to the capacitors are disposed on an identical plane while a positive electrode side wire and a negative electrode side wire of a DC power supply are disposed parallel to each other so as to extend along each arm has been proposed (see PTL 1, for example).